The broad Challenge Area to be addressed is 12: Science, Technology, Engineering and Mathematics Education (STEM). The specific Challenge Topic is 12-OD-101: Efficacy of educational approaches toward promoting STEM competencies. Research on efficacy testing of educational pedagogy, tools and curricula (both classroom and non- classroom approaches) that are targeted at improving student understanding of science, technology and engineering, and math (STEM) concepts. With the emergence of research-based materials developed by researchers within specific scientific disciplines (in this case, physics), based on research on students'understanding, science departments across the country are having to make decisions about whether or not to adopt the research-based materials. The materials have often been tested at the university at which they have been developed, but very few replication studies have been done to see if they successfully increase students'understanding at institutions other than the institution of origin. It is necessary that other institutions, particularly large institutions, perform replication studies to test the materials. We will rigorously assess four interventions for their efficacy at increasing students understanding of physics concepts, students'attitudes towards science and scientific reasoning and students'problem solving skills at a large university, where the interventions are implemented to many students. Three of the interventions involve the introduction of research-based materials and pedagogies into the laboratories in the large introductory courses. We will assess the students'conceptual understanding, attitudes about learning science, ability to reason scientifically and problem solving skills with control and treatment classes. In addition, we will assess the same skills of students in a laboratory-based, interactive-engagement course developed specifically for students who intend careers in the health sciences. It is important that physics departments pay more attention to introductory courses aimed at students in the health sciences. Many of these students will need physics concepts in their future careers. Areas of study involving both physics and biology, such as biophysics, are becoming more and more the choice of students. Students in the health sciences need a strong background in physics and physics departments need to give them the best education possible. The four interventions we will assess are: 1) The introduction of research-based laboratories and teaching pedagogies into the curriculum. 2) Teaching assistant training in the new pedagogies and the development and use of grading rubrics. 3) The integration of the lecture and the lab, using the new research-based laboratories and pedagogies. 4) A completely laboratory-based, interactive engagement course taught to students in small sections. Public Health Relevance: It is important that physics departments pay more attention to introductory courses aimed at students in the health sciences. Many of these students will need physics concepts in their future careers. Areas of study involving both physics and biology, such as biophysics, are becoming more and more the choice of students. Students in the health sciences need a strong background in physics and physics departments need to give them the best education possible. Our proposal is aimed at increasing students'understanding of physics content, and their scientific reasoning and problem solving skills. We will assess interventions that should increase students'skills in these areas. We will assess four interventions that include a laboratory-based, interactive engagement course designed specifically for students in the health sciences. We will assess the use of research-based materials in large classes, focusing on how large institutions can help increase the understanding of all students, but with a particular focus on students in the health sciences.